NAM/CAR AND SAM REGIONAL AIR NAVIGATION PLANS (SURVEILLANCE SYSTEMS)

NAM/CAR AND SAM REGIONAL AIR NAVIGATION PLANS (SURVEILLANCE SYSTEMS) NAM/CAR/SAM AUTOMATIC DEPENDENT SURVEILLANCE BROADCAST (ADS B) IMPLEMENTATION WORKSHOP (ADS B/IMP) (Lima, Peru, 13 to 16 September 2017) Onofrio Smarrelli CNS RO, ICAO SAM Mayda Avila CNS RO, ICAO NACC 1

CONTENTS CAR/SAM AIR NAVIGATION PLAN (SURVEILLANCE SYSTEMS) SAM REGIONAL PERFORMANCE BASED IMPLEMENTATION PLAN (SURVEILLANCE SYSTEMS) NAM/CAR REGIONAL PERFORMANCE BASED IMPLEMENTATION PLAN (SURVEILLANCE SYSTEMS) GREPECAS ORGANISATION (SURVEILLANCE SYSTEMS) IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS NAM/CAR REGIONS 2

CAR/SAM AIR NAVIGATION PLAN Air navigation plans lay out in detail the facilities, services, and procedures required for international air navigation in a given area. These plans contain recommendations that governments may follow when planning the provision of their air navigation facilities, with the assurance that the facilities foreseen in accordance with the plan, together with those of the other States, will create an integrated system that is appropriate for the foreseeable future. Each contracting State is responsible for the provision of facilities in its territory, in accordance with Article 28 of the Convention. The Council has recommended that these facilities include those specified in the air navigation plans. On 18 June 2014, the ICAO Council decided that regional air navigation plans (ANPs) would be published in three volumes, thus replacing the regional air navigation plans approved by the Council on 26 February 1997, made up by two volumes: a basic ANP and a facilities and services document (FASID). For the CAR/SAM Regions, the number of the Air Navigation Plan document continues to be 8733. 3

CAR/SAM AIR NAVIGATION PLAN Volume I contains the stable elements of the Plan, whose amendment requires the approval of the Council, related to: the assignment of responsibilities; mandatory requirements subject to regional agreement; and/or additionalregion specific requirements not covered by the SARPs. Partial list of these elements: boundaries (tables and charts) of flight information regions (FIRs); boundaries (tables and charts) of search and rescue regions (SRRs); Volcanic Ash Advisory Centres (VAACs); Tropical Cyclone Advisory Centres (TCACs); Volcano Observatories (VOs); 4

CAR/SAM AIR NAVIGATION PLAN Volume II contains the dynamic elements of the plan, whose amendment does not require the approval of the Council (approval is by regional agreement of the relevant PIRGs), related to: the assignment of responsibilities; mandatory requirements subject to regional agreement; and/or additional region specific requirements not covered by the SARPs. Partial list of these elements: Main traffic flows; Air traffic service (ATS) route network; Meteorological watch offices (MWOs); Secondary surveillance radar (SSR) codes; Five letter name codes; VOLMET broadcasts. Project title (Insert, Header & Footer) 5

CAR/SAM AIR NAVIGATION PLAN Volume III will contain the dynamic/flexible elements of the plan, providing guidance for planning the implementation and modernisation of air navigation systems, taking into account emerging programmes, such as ASBU, and the roadmaps of the associated technologies described in the GANP. Volume III of the ANP will also contain appropriate additional guidance material, mainly concerning implementation, to supplement the material contained in ANP Volumes I and II. Amendment of Volume III would not require approval by the Council but rather a regional agreement (Secretariat and PIRG). Project title (Insert, Header & Footer) 6

CAR/SAM AIR NAVIGATION PLAN VOLUME I PART III COMMUNICATIONS, NAVIGATION AND SURVEILLANCE (CNS) SURVEILLANCE 2.8 Planning of aeronautical surveillance systems must be based on a systems approach concept, giving consideration to collaboration and the exchange of data sources in support of an efficient use of airspace. PART IV AIR TRAFFIC MANAGEMENT (ATM) AIRCRAFT IDENTIFICATION SSR CODE ASSIGNMENT 2.5 Secondary surveillance radar (SSR) code management is a key element for ATM to ensure continuous and unambiguous aircraft identification. Requirements related to the system for assigning SSR codes used in the Region are contained in Volume II. Project title (Insert, Header & Footer) 7

CAR/SAM AIR NAVIGATION PLAN VOLUME II PART III COMMUNICATIONS, NAVIGATION AND SURVEILLANCE (CNS) General regional requirements Surveillance 2.40 An important element of the modern air navigation infrastructure required to safely manage the increasing levels and complexity of air traffic is aeronautical surveillance systems. 2.41 When operating Mode S radars, States should coordinate with their corresponding Regional ICAO Office the assignment of their interrogator identifier (II) codes and surveillance identifier (SI) codes, particularly in areas of overlapping coverage. Project title (Insert, Header & Footer) 8

CAR/SAM AIR NAVIGATION PLAN VOLUME II PART III COMMUNICATIONS, NAVIGATION AND SURVEILLANCE (CNS) Specific regional requirements Table CNS II CAR/SAM 1 ATN IPv4 addressing scheme Table CNS II CAR/SAM 2 Aeronautical mobile service and AMSS Table CNS II CAR/SAM 3 Radio navigation aids plan Table CNS II CAR/SAM 4 ASTERIX SAC code assignment Table CNS II CAR/SAM 5 Surveillance systems plan Table CNS II CAR/SAM 6 Geographical separation criteria Table CNS II CAR/SAM 7 VHF sub band allotment table Project title (Insert, Header & Footer) 9

CAR/SAM AIR NAVIGATION PLAN Table CNS II CAR/SAM 4 SAC ASTERIX code assignment plan State/Territory Estado/Territorio SAC Code Format Formato Código SAC Hexadecimal SAC Code Código SAC Hexadecimal B7 B6 B5 B4 B3 B2 B1 B0 Anguilla (United Kingdom) 1 1 1 0 0 0 0 0 E0 Antigua & Barbuda 1 1 1 0 0 0 0 1 E1 Argentina 1 1 1 0 0 0 1 0 E2 Aruba (Netherlands) 1 1 1 0 0 0 1 1 E3 Bahamas 1 1 1 0 0 1 0 0 E4 Barbados 1 1 1 0 0 1 0 1 E5 Belize 1 1 1 0 0 1 1 0 E6 Bolivia 1 1 1 0 0 1 1 1 E7 Brasil 1 1 1 0 1 0 0 0 E8 Cayman Islands (United Kingdom) 1 1 1 0 1 0 0 1 E9 Chile 1 1 1 0 1 0 1 0 EA Colombia 1 1 1 0 1 0 1 1 EB Costa rica 1 1 1 1 1 1 0 0 EC Cuba 1 1 1 0 1 1 0 1 ED Dominica 1 1 1 0 1 1 0 1 EE Dominican Republic 1 1 1 0 1 1 1 1 EF Ecuador 1 1 1 1 0 0 0 0 F0 El Salvador 1 1 1 1 0 0 0 1 F1 Guadeloupe, French Antilles (France) 0 0 0 0 1 0 0 0 08 Martinique, French Antilles (France) 0 0 0 0 1 0 0 0 08 French Guiana (France) 0 0 0 0 1 0 0 0 08 Grenada 1 1 1 1 0 1 0 1 F5 Guatemala 1 1 1 1 0 1 1 0 F6 Guyana 1 1 1 1 0 1 1 1 F7 Haiti 1 1 1 1 1 0 0 0 F8 Honduras 1 1 1 1 1 0 0 1 F9 Jamaica 1 1 1 1 1 0 1 0 FA Mexico 1 1 1 1 1 0 1 1 FB Montserrat (United Kingdom) 1 1 1 1 1 1 0 0 FC Netherland Antilles (Netherlands) 1 1 1 1 1 1 0 1 FD Nicaragua 1 1 1 1 1 1 1 0 FE Panama 1 1 1 1 1 1 1 1 FF Paraguay 1 1 0 1 0 0 0 0 D0 Peru 1 1 0 1 0 0 0 1 D1 Puerto Rico (United States) 1 1 0 1 0 0 0 1 D2 Saint Kitts and Nevis 1 1 0 1 0 0 1 1 D3 Saint Lucia 1 1 0 1 0 1 0 0 D4 Saint Vincent and Grenadines 1 1 0 1 0 1 0 1 D5 Saint Maarten 1 1 0 1 0 1 1 0 D6 Suriname 1 1 0 1 0 1 1 1 D7 Tortola 1 1 0 1 1 0 0 0 D8 Trinidad and Tobago 1 1 0 1 1 0 0 1 D9 Turks and Caicos Is. (United Kingdom) 1 1 0 1 1 0 1 0 DA United States (For sharing w ith CAR Region) 1 1 0 1 1 0 1 1 DB Uruguay 1 1 0 1 1 1 0 0 DC Venezuela 1 1 0 1 1 1 0 1 DD Virgin Island (United Kingdom) 1 1 0 1 1 1 1 0 DE Virgin Island (United States) 1 1 0 1 1 1 1 1 DF 10

CAR/SAM AIR NAVIGATION PLAN SURVEILLANCE SYSTEMS TABLE CNS II CAR/SAM 5 11

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION Ch. 1 Foreword Ch. 2 Air traffic in the SAM Region Ch. 3 Planning considerations Ch. 4 Air traffic management Ch. 5 Communications, navigation and surveillance Ch. 6 Meteorology Ch. 7 Search and rescue services Ch. 8 Aeronautical information services Ch. 9 Aerodromes and ground aids / Aerodrome operational planning Ch. 10 Development of human resources and competence management Ch. 11 Safety management Ch. 12 Environmental protection Ch. 13 Performance improvement areas (PIAs), modules and air navigation report forms (ANRF)

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION Attachment A Traffic forecasts in the SAM Region Attachment B Global plan initiatives and their relationship with the main groups Attachment C Performance framework form PFF Attachment D Description of modules considered for the SAM Region Attachment E Air navigation report forms (ANRF) Attachment F Glossary of acronyms Attachment G PBN concept of operations (CONOPS) for the SAM Region Attachment H List of reference documents

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION SAM CNS Planning Improvement of the aeronautical fixed service (PFF SAM/CNS/01) Improvement of the aeronautical mobile service (PFF SAM/CNS/02) Improvement of navigation systems (PFF SAM/CNS/03) Improvement of the air surveillance service (PFF SAM/CNS/04)

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION PFF CNS 04 SAM

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION BLOCK 0 MODULES SAM REGION

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION

PERFORMANCE BASED IMPLEMENTATION PLAN FOR THE SAM REGION RELATIONSHIP BETWEEN PFFs AND ASBU MODULES ASBU PIA1 PIA2 PIA3 PIA4 PFF PFF SAM ATM/01 B0 RSEQ B0 APTA B0 SURF B0 ACDM B0 FICE B0 DATM B0 AME T B0 FRTO X B0 NOPS B0 ASUR B0 SNET B0 OPFL X B0 CD O B0 CC0 B0 TBO PFFSAMATM/02 X X PFFSAM ATM/03 X PFF SAM ATM/04 X PFF SAM ATM/05 PFF SAM ATM/06 X X X X X X PFF SAM CNS/01 X X X PFFSAM CNS/02 X PFF SAM CNS/03 X PFF SAM CNS/04 X X X PFFSAM MET/01 X PFF SAM MET/02 X X X PFF SAM MET/03 X X PFF SAM MET/04 X X X

NAM/CAR REGIONAL PERFORMANCE BASED AIR NAVIGATION IMPLEMENTATION PLAN The RPBANIP establishes the NAM/CAR regional priorities described as Regional Performance Objectives (RPO) to be accomplished during the period 2013 to 2018, aligned with the global air navigation priorities, agreed regional performancebased metrics and indicators, and the ICAO ASBU Air Navigation Reporting Forms (ANRFs).

NAM/CAR REGIONAL PERFORMANCE BASED AIR NAVIGATION IMPLEMENTATION PLAN RPOs and ASBU Methodology The Regional Performance Objectives RPOs provide the high level tasks for implementing the regional priorities, establishing the expected operational benefits and the metrics for progress measurements, benefits and achievements. In many cases, the RPOs contain the baseline elements to be implemented for the different B0 ASBU modules adopted by the NAM/CAR Regions. Initially for the 5 year term of the RPBANIP, 15 ASBU B0 modules have been adopted. The ASBU B0 modules ASEP, OFPL and WAKE will be included in future reviews of the RPBANIP based on the maturity of tasks and regional priorities.

NAM/CAR REGIONAL PERFORMANCE BASED AIR NAVIGATION IMPLEMENTATION PLAN RPOs related to surveillance and automation of ATS Systems

NAM/CAR REGIONAL PERFORMANCE BASED AIR NAVIGATION IMPLEMENTATION PLAN RPOs related to surveillance and automation of ATS Systems

NAM/CAR REGIONAL PERFORMANCE BASED AIR NAVIGATION IMPLEMENTATION PLAN

NAM/CAR REGIONAL PERFORMANCE BASED AIR NAVIGATION IMPLEMENTATION PLAN

GREPECAS ORGANISATION 25

PROJECT RLA/06/901 SAM/IG MEETINGS IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION Performancebased navigation (PBN) Air traffic flow management (ATFM) Improvement of CNS systems ATS automation 26

IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION DOCUMENTS PREPARED IN THE SAM REGION TO SUPPORT THE IMPLEMENTATION OF SURVEILLANCE AND ATM AUTOMATION SYSTEMS (Available at www.icao.int/sam in the CNS section of e Documents) SYSTEM INTERFACE CONTROL DOCUMENT (SICD) CONTAINS DETAILED INFORMATION ON THE INTERFACE BETWEEN THE RADAR SENSOR (PRIMARY/SECONDARY RADAR) AND THE ATCS (ATC CONTROL SYSTEM), THE INTERFACE BETWEEN THE AUTOMATIC MESSAGE SWITCHING CENTRE (AFTN) AND THE ATCS, THE OLDI INTERFACE BETWEEN AIR TRAFFIC CONTROL SYSTEMS, THE AIDC INTERFACE BETWEEN AIR TRAFFIC CONTROL SYSTEMS, THE INTERFACE BETWEEN FLIGHT PLAN PROCESSORS, THE INTERFACE BETWEEN THE RADAR SENSOR MONITORING AND CONTROL SYSTEM AND THE MONITORING AND CONTROL UNIT, THE INTERFACE BETWEEN THE CLOCK SYNCHRONISATION SERVER AND THE ATCS. INITIAL PLAN FOR REGIONAL INTERCONNECTION OF AUTOMATED SYSTEMS IN THE ACCs DESCRIBES A RECOMMENDED STRATEGY FOR THE IMPLEMENTATION OF THE INTERCONNECTION OF AUTOMATED SYSTEMS BETWEEN ADJACENT ACCs, TAKING INTO ACCOUNT THE CURRENT AND FORESEEN STATUS OF AUTOMATED SYSTEMS, BASED ON THE AUTOMATED SYSTEMS CURRENTLY INSTALLED IN THE ACCs OF THE REGION PRELIMINARY DOCUMENT ON AUTOMATED SYSTEM SPECIFICATIONS (SSS) THE DOCUMENT PRESENTS THE MINIMUM SPECIFICATIONS OF AN AUTOMATED CENTRE. IT IS ADDRESSED TO THE STATES OF THE REGION THAT HAVE AUTOMATED SYSTEMS IN THE ACCs SO THAT THEY CAN MAKE SURE THEY HAVE SUCH SYSTEMS, AND TO THOSE STATES THAT HAVE NOT YET IMPLEMENTED AUTOMATED SYSTEMS IN THEIR ACCs. 27

IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION DOCUMENTS PREPARED IN THE SAM REGION TO SUPPORT THE IMPLEMENTATON OF SURVEILLANCE AND ATM AUTOMATION SYSTEMS (Available at www.icao.int/sam in section CNS of e Documents) MEMORANDUM OF UNDERSTANDING FOR THE IMPLEMENTATION OF THE INTERCONNECTION OF AUTOMATED SYSTEMS BETWEEN TWO STATES THAT HAVE ADJACENT ACCs (MOU) THE MEMORANDUM OF UNDERSTANDING IS A GUIDE FOR STATES OF THE REGION TO ENTER INTO BILATERAL AGREEMENTS, TAKING INTO ACCOUNT ASPECTS CONTAINED IN THE DOCUMENTS ON THE INTERCONNECTION OF AUTOMATED SYSTEMS. THE MOU CONTAINS INFORMATION ON TECHNICAL, OPERATIONAL, ADMINISTRATIVE, INSTITUTIONAL AND FINANCIAL ASPECTS REQUIRED FOR BILATERAL IMPLEMENTATION OF THE INTERCONNECTION OF AUTOMATED SYSTEMS BETWEEN ADJACENT STATES OF THE REGION THAT HAVE INSTALLED AUTOMATED SYSTEMS IN THEIR ACCs. GUIDE ON TECHNICAL OPERATIONAL CONSIDERATIONS FOR ADS B IMPLEMENTATION IN THE SAM REGION PRESENTS INTRODUCTORY INFORMATION ON CONCEPTS AND TECHNICAL OPERATIONAL CONSIDERATIONS THAT SHOULD BE TAKEN INTO ACCOUNT BEFORE PLANNING AND IMPLEMENTING ADS B AS ATS SURVEILLANCE SENSOR OR AS ON BOARD TRAFFIC MONITORING SYSTEM TO IMPROVE SITUATIONAL AWARENESS OF THE CREW. GUIDE ON TECHNICAL OPERATIONAL CONSIDERATIONS FOR MLAT (MULTILATERATION) IMPLEMENTATION THE PURPOSE OF THIS DOCUMENT IS TO PROVIDE BASIC INFORMATION TAKEN FROM DOCUMENTS ISSUED BY ICAO AND OTHER ENTITIES REGARDING GENERAL ASPECTS OF AERONAUTICAL SURVEILLANCE SYSTEMS FOR AIR TRAFFIC CONTROL (ATC), AIRCRAFT AND, PARTICULARLY, A MULTILATERATION (MLAT) SYSTEM IN SUPPORT OF AIR TRAFFIC CONTROL. 28

IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION ADS B TESTS IN PERU PROJECT RLA/06/901 29

IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION ADS B Implementation Action Plan SAM Region IMPLEMENTATION PHASE PHASE I Conduction of ADS B trials, data collection and processing, and presentation of results TASK ACTIVITY 1 Define trial objectives, to see the possibility for States to derive benefits from ADS-B as surveillance system in the Region. 2 Review and detail the activities to be considered for ADS-B trials conducted by the GREPECAS mechanism. 3 Determine the equipment and configuration required for starting trials. Obtain trial costs. 4 Define the geographical area where trials are to take place. 5 Consult States and users on their interest to participate in the trials. 6 Select the entities, organisation or States in charge of conducting the trials. RESPONSIBLE PARTY CNS Task Force Secretariat EXPECTED RESULT Trial objectives Regional plan of ADS-B trial activities reviewed Rapporteur Definition of equipment and configuration for the trial Rapporteur Secretariat STATUS Finalised Finalised Finalised Thales ADS-B station was used for the trial at no cost. Geographical Finalised area defined The terminal (CONOPS) area of the Jorge Chavez international airport in Lima, Peru, was considered. Confirmation Finalised of participation by States States Selection of Finalised the entity, The air organisation or navigation State. service provider of Peru (CORPAC) was selected.

IMPLEMENTATION OF SURVILLANCE AND AUTOMATION SYSTEMS SAM REGION PHASE I Conduction of ADS B trials, data collection and processing, and presentation of results 7 Installation of the ADS-B equipment required for the trial in the defined geographical area. 8 Conduction of trials (data collection). 9 Processing of the data collected. 10 Presentation of the results obtained. Selected entity, organisation or State State (Peru) Manufacturer (Thales) Secretariat State (Peru) Manufacturer (Thales) Secretariat State (Peru) Secretariat Equipment installed Start-up trials Processing data of of Presentation of results Finalised Installed at the Jorge Chavez international airport in Lima, Peru. Finalised Trials were conducted for a period of six months. Finalised The collected data was processed by the air navigation service provider (CORPAC). Finalised The results were presented at the ADS-B workshop in Lima, Peru, and SAM/IG meeting.

IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEM SAM REGION PHASE II OPERATIONAL IMPLEMENTATION OF ADS B 11 Define operational use of ADS B based on the airspace concept defined at national level 12 Safety assessment based on the defined operational use 13 Development of model document for ADS-B operational implementation Development of model advisory circulars for airworthiness and ADS-B operation approval Development of model AIC to communicate ADS- B implementation planning Develop model AIP supplement containing the applicable standards and procedures for ADS B according to the defined operational use Review procedural handbooks of ATS units according to the operational use defined for ADS B States State Regional projects RLA/99/901 RLA/06/901 States Presentation of results Presentation of results Publications in support of ADS B implementation Valid Valid In this task, it is important to analyse the behaviour of global positioning satellites in these latitudes. Valid June 2017 All model publications on the operational use of ADS B.

IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION PHASE II OPERATIONAL IMPLEMENTATION OF ADS B 14 Publication of States Publication of documents in support of documents the operational implementation of ADS B 15 Training programme: Regional Training Establishment of a projects programme training programme RLA/99/901 for ATS staff for the RLA/06/901 operational States implementation of ADS B according to the defined operational use Establishment of a training programme for airworthiness and operations personnel for the operational implementation of ADS B according to the operational use Establishment of a training programme for pilots for the operational implementation of ADS B according to the defined operational use. 16 ADS B implementation States Operational implementation of ADS B Valid December 2017 Valid December 2017 Valid 2024 PHASE III FOLLOW-UP TO ADS B IMPLEMENTATION 17 Follow-up to ADS B implementation SAM/IG Secretariat Follow-up to ADS B implementation Valid 2024

RADAR COVERAGE SAM REGION IMPLEMENTATION OF SURVEILLANCE AND AUTOMATION SYSTEMS SAM REGION 34

IMPLANTACIÓN DE SISTEMAS DE VIGILANCIA Y AUTOMATIZACION EN LAS REGIONES NAM/CAR GRUPOS DE IMPLEMENTACION Y APOYO NAM/CAR http://www.icao.int/nacc/pages/ nacc regionalgroups aniwg.aspx

IMPLANTACIÓN DE SISTEMAS DE VIGILANCIA Y AUTOMATIZACION EN LAS REGIONES NAM/CAR http://www.icao.int/nacc/pages/regional groups.aspx

https://www.icao.int/nacc/pages/nacc regionalgroups aniwg.aspx IMPLANTACIÓN DE SISTEMAS DE VIGILANCIA Y AUTOMATIZACION EN LAS REGIONES NAM/CAR

https://www.icao.int/nacc/pages/regional-group-adsb.aspx

Cobertura Radar en los Flujos de transito primarios IMPLANTACIÓN DE SISTEMAS DE VIGILANCIA Y AUTOMATIZACION EN LAS REGIONES NAM/CAR

IMPLANTACIÓN DE SISTEMAS DE VIGILANCIA Y AUTOMATIZACION EN LAS REGIONES NAM/CAR Implementación Radar Modo S: 7 Radares SSR Modo S en Centroamérica 2 Radares SSR Modo S en Bahamas 1 Radares SSR Modo S en Trinidad y Tabago Varios Radares SSR Modo S en México Implementación ADS-B : Aruba Centroamérica Cuba Haití Jamaica México Trinidad y Tabago

IMPLANTACIÓN DE SISTEMAS DE VIGILANCIA Y AUTOMATIZACION EN LAS REGIONES NAM/CAR Resultado NACC/WG/5 41